Automatic variable pump



May 7, 1946. 9 M. M. CULVER v 9 2,399,990

AUTOMATIC VARIABLE PUMP Filed Nov. 12, 1943 4 sheets sheet 1 M y .M; M.CULVER 2,399,990

AUTOMATIC VARIABLE PUMP v Filed Nov. 12, 1943 4 Sheets-Sheet 2 Sums?err/9m 16 e011. 3/ 30 1.5 3mm Marg m. calm;

May 7, 1946. M. M. cum/ER AUTOMATIC VARIABLE PUMP 4 Sheets-Sheet 3 FiledNov. 12, 1943 llli y 7, 1946. A M. M. CULVER 2,399,990

AUTOMATIC VARIABLE PUMP JFiled Nov. 12, 1945 4 Sheets-Sheet 4 PatentedMay 7, 9 1946 AUTOMATIC VARIABLE PUMP Merlyn M. Culver, Dayton, Ohio,assignor' to United Aircraft Products, 'Inc., Dayton, Ohio, a

corporation of Ohio Application November '12, 1943, Serial No. 510,003

2 Claims.

-.This invention relates to pumps, and has par-. ticular. reference toimprovements in variablestroke, variable-capacity pumps of the typecomprising a cylinder, a rotor rotatable therein and providedwith radialor transverse displacement chambers, pistons in said displacementchambers rotatable with said rotor, and means wherebysaid pistons arereciprocable in said chambers in response to their rotation with saidrotor to accomplish their pumping function.

In many instances it is very desirable to employ a pump, the output ofwhich may readily be varied to maintain the fluid being pumped underconstantor substantially constant pressure despite variations in thedemand upon the pump and without dependence upon sudden and more or lesswidely varying changes in the speed of operation of the pump. Forexample, in the internal combustion engine art in general andparticularly in, the aircraft art, it is very desirable to employ anengine fuel pump which will deliver fuel to the engine under constant orsubstantially constant pressure and in accordance with more or lesssudden and more or less wide variations in the fuel demands of theengine, whether variations in the fuel demands are due to more or lesssudden and more or lesswidely varying changes in the speed of theengine, to variations in the load thereon, or to other causes.

Accordingly, one special and important object of the present inventionis to provide a pump of the type mentioned, especially for use as a fuelpump for internal combustion engines in general and particularly foraircraft engines, but, 'of course, capable of various other uses, whichis operable in response to variations in the pressure of the fluid beingpumped rather than to variations in its speed of operation, to vary thestroke of its pistons and thereby vary its output, thus automatically tovary its delivery of fluid in accordance with variations in the demandtherefor and to'maintain the delivered fluid under constant orsubstantially constant pressure.

Another special and important object of the invention is to provide apump of the character mentioned which, in general, is of simple,practical construction and which embodies simple, practical means forvarying the stroke of its pistons in response to variations in thepressure of the fluid being pumped.

Another special and important object of the invention is to provide apump of the character mentioned which is reversible and which includesby-pass means whereby fluid may be pumped or otherwise circulatedtherethrough between the inlet and the outlet thereof when the same isidle. Another special and important object of the invention .i toprovide a pump of the character mentioned embodying simple means to sealthe same eifectively against. leakage of fluid therefrom.

Another special and important object of the invention is to provide apump of the-character mentioned which is strong, rugged and thoroughlyreliable and efficient in operation.

With the foregoing and other objects in view, the invention consists ina pump of the character mentioned embodying the various novel featuresof construction, combination and arrangement of parts as will behereinafter more fully described, illustrated in the accompanyingdrawings and defined in the appended claims.

In the accompanyingdrawings, wherein like characters of referencedenote; corresponding parts in the different views:

Fig. 1 is a side elevation of a pump constructed in accordance with onepractical embodiment of the invention.

Fig. 2 is a diagrammatic view illustrating the pump embodied in a fuelfeeding system of an aircraft engine.

Fig. 3 is a top plan view of the pump.

Fig. 4 is a central, vertical, longitudinal sec-' of the plug unit forclosing the outer end of the pump cylinder.

Fig. 8 is a central. vertical, transverse section through the pump withthe pressure responsive means for varying the stroke of the pistonspositioned as shown in Fig. 4.

Fig. 9 is a perspective. view of the rotor and piston elements of thepump shown in separated relationship to each other; and

Fig. 10 is a perspective view of the closure cap unit illustrated inFig. 7 with the parts thereof chamber, respectively, and either of whichmay be for the inlet of fluid to the pump and the other for the outletof fluid therefrom.

At what may be termed its inner and its outer ends, the cylinder II isclosed by what may be termed plug units I4 and i5, respectively, whichare duplicates of one another except as regards the main element of eachof them, which main elements merely are specifically different from eachother to adapt the units for convenient and practical mounting in therespective ends of said cylinder. In other words, each of said plugunits includes a main element in the form of a relatively thick,circular plate l6 fitted snugly in the cy1in--- der II, and whereas thisplate of the unit l5 includes a flange I! to overlie and to be boltedagainst the outer end wall of the cylinder ID to secure said unit |5firmly in place in closing relationship to the outer end of the cylinderII, the corresponding plate of the unit I4 is disposed entirely withinthe cylinder H and, therefore, is devoid of any such flange. In otherrespects the units l4, l5 are, in all essential respects and to allessential intents and purposes, reversed duplicates, or substantiallyreversed duplicates, of each other, the unit l4 being secured firmly inplace in closing relationship to the inner end of the cylinder III byreason of the plate l6 thereof being disposed against an inwardlyextending, annular, flange-like wall l8 of the casing l and by beingfastened against said wall by bolts or screws |9.

Each plug unit |4, includes a block 20 securely fastened by means ofscrews 20 or inany other suitable manner against the inner face of itsrelated plate l5 and having in the face thereof adjacent to its relatedplate I6 a channel 2| extending from top to bottom thereof. Thus, ineach plug unit l4, l5, between the plate It and the block 20, isprovided a guide channel extending from top to bottom of the'unit.

Slidably mounted in each guide channel 2| for vertical movement is aslide-piece 22, and projecting laterally inward from each slide piecethrough an opening 23 in the wall of the related block 20 defining theinner side of the channel 2| and inwardly beyond said wall, is acircular boss 24 on which is rotatably mounted a flat circular band 25.The openings 23 are of greater dimensions vertically than the diametersof the bands 25 to permit vertical movements of the slidepieces 22 andof the bosses 24 with the bands 25 thereon relative to the blocks 20.

Coaxial with the cylinder II is a shaft 25 which extends throughopenings 2!v in the slide-pieces 22 and the bosses 24 and which isjournaled for rotation in central bearings in the plates l6. Carried bythis shaft is the pump rotor, desigv pistons.

nated generally as 28. This rotor is of cylinthe shaft 25 extends, andsaid rotor is suitably fastened to said shaft for rotation therewith as,

for example,'by means of apin 32' extending transversely through alinedholes in said hub and said shaft. I

The pump pistons 3| are of the same length as the rotor 29 and of thesame width as the slots or displacement chambers 29, 30 so as to engagefluid-tightly at their sides with the walls defining the sides of saidslots or displacement chambers and at their ends with the inner faces ofthe blocks 20, and are of lesser depth than said slots or displacementchambers 29, 30 so as to be reciprocable therein, their outer facespreferably being curved transversely on the same radius as the cylinderH and the rotor 28. These pistons are connected together in two oppositepairs, each pair by a. web 33 located adjacent to one end of the pair soas to clear the web or hub 32 of the rotor 29, and the two pairs aredisposed in the slots or displacement chambers 29, 30 in right angularrelationship to each other with the pistons of each pair occupyingpositions diametrically opposite of said slots or displacement chambers,the webs 33 of the respective pairs being disposed at opposite sides ofthe web or hub 32 of the rotor 28. In the webs 33 are openings 34through which the shaft 25 extends and which are amply long so that saidshaft does not interfere with reciprocation of the pistons. Obviously,when the rotor 28 rotates, the pistons 3| rotate therewith.

At their ends, the pistons of each pair straddle the bands 25 andcontact with the peripheries thereof, the distance between the bandcontacting inner face portions 35 of each pair of pistons being equal tothe diameters of said bands which are equal in diameter to each other.Accordingly, if the slide-pieces 22 are adjusted to dispose the bosses24 and the bands 25 eccentrically with respect to the shaft "and therotor 28, rotation of said rotor and the pistons 3| therewith willresult in radial reciprocation of said pistons in the slots ordisplacement chambers 29, 30 due to the coacting cam action between thebands 25 and the end portions 35 of the pistons. If, on the other hand,the slide-pieces 22 are adjusted to dispose the bosses 24 and the bands25 concentrically with respect to the shaft 26 and the rotor 28,rotation of said rotor and the pistons 3| will not result in anyreciprocable movement of said It will be apparent, therefore, that thestroke of the pistons 3|, between zero and maximum, is variable byvertical sliding adjustments of the slide-pieces 22 in their channels2|. 0bviously, the bands 25 may be eliminated and the ends of thepistons 3| may directly engage the bosses 24. The bands 25 preferablyare used, however, because they may readily be hardened to reduce wearand because they may readily be removed.

Formed in the casing I0 at opposite sides of the cylinder II inalinement with the openings l2 and I3 and opening into said cylinder II,is a pair of circumferentially extending channels 36, 36 of any suitablewidth and depth the upper and lower ends of which, at the bottom and thetop,

' respectively, of said cylinder II, are spaced apart ment chambers 29,30. Thus, rotation of the asoaeoo a pair of arms 4|, 4| which aresuitably connected,

to the slide-pieces 22 as, for example, by means of Preferably thepiston 41 is bored from its top to accommodate the lower' end portion ofthe spring 43 and preferably means is provided to vary the strength ofsaid spring to determine the pressure of the pumped liquid required toreduce the stroke of the pump pistons 3 I.

screws, rods or other suitable connecting elements 42 which extendslidably' through openings in the top wall of the casing I 3. Thus,flexure of the diaphragm 43 is effective to produce vertical adjustmentsof the slide-pieces 22 and of the bosses 24 and the bands 25 carriedthereby to vary the stroke of the pump pistons. In this connection itwill be observed that a spring 43 is provided to act downwardly upon thediaphragm 43 and the arms 4| to tend constantly to urge the slidepieces22 to their limits of downward movement v for maximum stroke of the pumppistons and thatand that a pivoted or flap type check valve 43 iscapable of being pivoted to either of a pair of supports 36, 43 in thechamber 33 so as to cooperate with either of the ducts 44 topermit'flowof fluid through the same into the pressure chamber 33 and to deny flowof fluid through the same from saidpressure chamber. This checkvalve ispivoted to cooperate with the duct 44 which is related to the channel 36at whatever'ma'y be the inlet side of the pump, depending upon thedirection of rotation of the rotor 28. Accordingly, the chamber 331ssubjected to the pump outlet pressure of the fluid being pumped and if,for any reason, this pressure exerts a force upwardly upon the diaphragm40 in excess of the spring pressure thereon, said diaphragm will flexupwardlywith consequent raising of the slide-pieces 22 and reduction inthe stroke of the pump pistons commensurate with the difl'erence inpressures above and below said diaphragm. Thus, not only the quantity offluid pumped by the. pump is controlled automatically in response tovariations in the pressure of'the pumped fluid at the outlet side of thepump, but the consequent tendency is tomaintain a substantially constantor uniform pressure of the pumped fluid.

Preferably, but not necessarily, means isassociated with the diaphragm43'to render the same smoothly acting in operation, and. this means maycomprise, for example, a dash-pot consisting of a piston 41 suitablysecured to said diaphragm and depending therefrom into a cylinder 41'formed in the upper wall of the casing III, the said cylinder being incommunication at its bottom with the chamber 33 through a small duct 43.

- Conveniently, the arms 4| may be formed as integral parts of thepiston 41. Conveniently, too,

the housing 31 may be of two-part construction comprising lower andupper parts 43 and 53. respectively, between which the diaphragm 43 maybe marginally clamped.

While any suitabl means may be provided for varying the strengthof thespring 43, one suitable means for this purpose may comprise, as shown,an abutment disk 5| for the upper end. 01 said spring keyed or otherwisemounted in a vertical bore 52 of the upper housing part 53 fornon-rotatable, vertical sliding movement in said bore, and a screw 53swiveled to said upper housing part and threaded through said disk.Thus, by rotatably adjusting said screw, said disk may be adjustedvertically to var the strength of said spring 43. The screw 53 may havea flange 54 interposed between the top of an exteriorly threaded neck 55at the top of the upper housing part and an inwardl extending flange 56of a unit 51 threaded on said neck to provide a swiveled connectionbetween said housing part and .said screw, this arrangement being simpleand by tightening said nut, said screw may readily be fastened againstrotation in any rotatably adjusted position thereof.

Th shaft bearing opening in the plate iii of the plug unit. I5 is closedat its outer end and therefore there is no possibility oi leakage offluid from the pump around said shaft at this point.

: On the other hand, the shaft bearing opening in the plate l3 of theplug unit I4 extends entirely through said plate and therefore it isnecessary to seal said opening against leakage of fluid from the pumptherethrough. In this connection it this connection being afforded, forexample, by a tongue 59 on the end of the shaft 28 engaged in a slot inthe end of the shaft extension 26'.

In an annular channel in the inner face of thecap-piece 53 insurrounding relationship to the shaft extension 23' is disposed asuitable gasket 33, while on the shaft extension 26' is an annularflange 3i which bears against the inner edge of said gasket. Inaddition, a cup member 32 is mounted on the shaft 26 with its closed andfacing inwardly and bearing against an annular rib 33 on the outer faceof the plate It and with its open end facing outwardly. In this cupmember and surrounding the shaft 26 is a suitable gasket 54, whilebetween said gasket and the flange 3! is interposed an expansion coilspring 63 which tends constantly to urge the shaft extension 2-3'outwardly and the gasket 34 and the cup member 52 inwardly. Since inwardmovement of the cup member 32 is limited by the plate i3, one effect ofthe spring 35 is to maintain the gasket 34 under compression in tightlysealing. engagement with the shaft 23 and, at the same time, to maintainthe inner face of the cap member 32 in tightly sealing engagement withthe rib 33. The other effect of said spring 33 is to urge the shaftextension 23 outwardly, with V the result that the flange 3| maintainsthe gasket 33 under compression in tightly sealing engagement with saidshaft extension and with the surrounding portion oi the cap=piece E8.Thus, even though. any fluid may lea-l2 the cylinder ii into the chambercontaining the spring 65 and the seals, any leakage of fluid from saidchamber eii'ectively is prevented.

The shaft extension 28 projects outwardly beyond the cap-piece 58 forconnection with any suitable power unit for driving the pump, andopenings 6? preferably are provided in the casing It for the supply oflubricant to the chamber 86 and for the drainage of said chamber.

Fig. 2 of the drawings illustrates a conventional fuel feeding systemfor an aircraft engine including a pump constructed in accordance withthe invention. In Fig. 2 an internal combustion engine is indicated asA, a supercharger is indicated as B, a fuel tank is indicated as C, apower driven fuel pump constructed in. accordance with the inventionislndicamcl as D, and. a hand= pump for use in the event of failure ofthe pump D or for engine starting or other purposes, is indicated as E.

A pipe at connects the fuel tank C with the inlet side of the hand=puropE, and the inlet side of said hand puznp is a bypass passageway b whichis connected with the inlet side of the pump D by a pipe 6. Another pipee connects the outlet side of the hand=pump with the inlet side of thepump a pipe fcoDnect-s the outlet side of the pump D with the e; ic A.Grdinarily, the pump D functions to fuel ss 2) under substantiallyconstant or uniform pressure. At times, however, may he necessaiy ordesirable to employ l1 d-pump E to deliver fuel to the engine, ch eventthe iiow is via the pipe (2 to the ini t side of said handpump, from theoutlet side to the inlet side of the pump D via the pipe 2, through thechannel 36 and the duct at the inlet si no of said pump D, then into thechamber past the check valve it, through duct i l and the channel theoutlet side of said pump D, and then to engine the pipe f.

The superch. B is connected with the upper chamber 3 of the pump D by apipe 9. Therefore, said chamber is subjected to supercharger pressurewhich acts downwardly upon the diaphragm 36 and augments the spring inthis respect. Consequently, variations in the stroke of the pistons of.the D is a function ofthe difference between the pressm'e of the-fluidat the outlet side of said on the one hand, and the combined pressure ofthe spring and the supercharger B on. the other hand, in any instancewhere a supercharger or other pressure device is connected 4 the chamber35?. In this cormectionit is manifest that, for many purposes, thechamber 59 may not he necessary and may be eliminated if desired.

From the foregoing description considered in connection with theaccompanying drawings, it is believed thatthe construction and operationof the present pump will be clearly understood and its advantagesappreciated. It is desired to point out, however, that while only asingle, specific embodiment of the invention has ceen illustrated anddescrihed, the same is readily capable of embodiment in various otherspecifically different mechanical form within its spirit and scope asdefined in the appended claims.

1'. claim:

1. A variable capacity pump, comprising a housing defining a cylinderhaving inlet and outlet ports therein; a rotor in said. cylinder, theperipheral surface of which is in continuous contact with the wall ofsaid cylinder; longitudinal slots in the peripheral surface of saidrotor; pistons radially movable in said slots and carried by said rotorsuccessively past said inlet and outlet ports; means eccentric withrespect to the longitudinal axis of said rotor providing a mount forsaid pistons whereby to impart a pulsating motion thereto so that fluidis drawn into said slots at said inlet port and expelled therefrom atthe outlet port, the length of strokes of said pistons determining therate of flow of fluid through the pump; operating fingers extending intosaid cylinder into cooperative relation with said piston mounts forshifting said mounts toward and from a position more nearly coaxial withsaid rotor to shorten and lengthen the strokes of said pistons; andfluid pressure operated means for controlling action of said operatingfingers.

2. A. variable capacity pump, comprising a housing defining a cylinderhaving inlet and outlet ports; a rotor in said cylinder movable about afixed axis; a pair of diametrically opposed slots in said rotor; pistonsin said slots connected for simultaneous operation, said pistons beingmovable transversely of the axis oi said rotor and carrim by said rotorsuccessively past said inlet and outlet ports; a pair of cylindricalpiston mounts at the opposite ends of said rotor and adjustable radiallythereof toward and from positions coaxial with the rotor, the ends ofsaid pistons being in sliding engagement with said cylindrical mountsand guided thereby through radim strokes which are variable in length inaccordance with the position 05 the piston mounts with respect to theaxis of the rotor; a single spring means pressing said piston mounts topositions effecting radial strokes of a maximum length of said pistons;and fluid pressure operuteri means opposing the action of said springmeans.

I /LERLYN M. CULVER.

